Process for treating synthetic continu-



United States Patent F 3,103,448 PROCESS FOR TREATING SYNTHETIC CONTINU- GUS FILAMENT YARNS AND RESULTING PRODUCT Stanley E. Ross, East Orange, N.J., assign'or to Allied Cheinical Corporation, New York, N.Y., a corporation I of New York No Drawing. Filed Sept. 12, 1960, Ser. No. 55,163 9 Claims. (Cl. 117-1395) This invention relates to the treatment of synthetic yarns of the continuous filament type, and more particularly to a process for rendering such yarns more durable when fabricated into cord or rope and more resistant to wet and dry chafing abrasion when processed into such commodities.

Heavy ropes and cordage have been fabricated in the past primarily from natural vegetable fibrous materials, such as hemp, jute, etc., and have depended'for their strength largely on fibre to fibre friction. In recent years, continuous synthetic filament yarns such as nylon, Dacron, etc., because of their high filament strength, have come into use in the manufacture of tire cord, rope and the like. The strength of such ropes depends largely on the combined strength of the individual filaments, and excessive breakage of such filaments tends to reduce the strength and shorten the llVGSOf the ropes ofwhich they form a part.

Heavy duty ropes and cords, such as are used as marine hawsers and the like are subject .to severe stresses in tension and abrasion, and to frequent wetting during such stresses. When undergoing such stresses, the continuous synthetic filaments are subjected to severe filament to filament friction tending to cause filament breakage when the rope stretches under such strains. In the case of nylon particularly, filament to filament friction is often so severe as to cause excessive temperature development sufficient to soften or melt the filament at the points of frictional contact. Under such conditions, even dry rope will sufier some breakage of filaments due to the strain. However, since nylon is appreciably tenderized or liquefied or dissolved in water at the elevated temperatures often-created 3 ,103,448 Patented Sept. 10, 1063 "Ice;

mally solid, hard, waxy polymers of ethylene, which are saturated aliphatic compounds characterized by a recurring CH group and which have average molecular weights between about 1,000 and about 3,000, especially polyethylene/alka'nol telomers of this character, are subjected, in the liquid phase, to the action of an oxygencontaining gas to cause reaction of at least about 5 pounds of oxygen per 100 pounds of wax, preferably between about 5 pounds and about 17 pounds of oxygen, per 100 pounds of wax, i.e. to provide an oxidized polyethylene wax containing at least about 3%, preferably between about 3% and about 9% of oxygen by weight, based on the weight of the oxidized wax, and acid numbers of not more than about 50, preferably between about 1-0 and internally in the rope by such friction, such frictional heat, occurring when the nylonis wet or immersed in water, may cause severe disintegration of the filaments at such points. Asa result of these conditions, ropes and hawsers' made from synthetic continuous filaments, and particularly nylon, tend to deteriorate not only in appearance by the formation of a fuzz or broken filaments, but

to be severely weakened in strength after relatively short periods of usage, particularly under wet conditions.

-I have now found that synthetic continuous filament yarns, especially nylon yarns, may be rendered more durable, and resistant to wet and dry filament breakage and resultant degradation in strength according to'my invention wherein the yarn is subjected, prior to its fabrication into cordage, to treatment with an aqueous emulsion of a readily emulsifiable, oxidized polyethylene wax, preferably followed by heating to a temperature above about 100 C. to evaporate excess water from the yarn.

Oxidized polyethylene wax materials suitable for use in my invention are described in co-pending application Serial No. 515,770 of Michael Erchak, In, filed June 15, 1955, now US. Patent No. 3,060,163, according to which norabout 45. The'oxidized polyethylene/isopropanol telomer Waxes prepared according to the above method containing between about 3% and about 6% oxygen and having average molecular weights between about 1,000 and about 3,000, melting points between about C. and about C., acid numbers between about 10 and about 20, are especially preferred. The preferred oxidized wax products are characterized by an extremely low incidence of, or in many cases, substantially complete absence of ester groups. Thus, the saponification' number (which measures both acid and ester groups) is substantially identical to or only slightly greater than the acid number (which measures only acid groups) so that these products all have an extremely low or zeroester number (saponification number minus acid number) and have ratios of saponification number to acid number of about 1 to about 1.2 and not more than about 1.5.

The waxy ethylene polymers which are oxidized as above described, may themselves be prepared by any suitable known methods, for example by subjecting ethylene, either alone, or in the presence of a co-reactant to temperatures between about C. and about 300 C. and pressures ranging from about 500 p.s.i. to about 7,000 p.-s.i. as disclosed in US. Patents 2,683,141 and 2,504,400 of Michael Erchak, Jr.

In carrying out the process according to my invention, the oxidized polyethylene wax as described, is emulsified in water by known methods using any suitable emulsifying agent. In general, I prefer to melt the polyethylene wax together with the emulsifying agent and then pour the melted wax gradually with stirring into hot water at a temperature slightly below the boiling temperature. Concentration of the wax component in the emulsion is not critical, and will be adjusted to provide the desired coat weight on the yarn under the particular application conditions employed. Concentrations between about 5% and about 20% are suitable, and between about 10% and about 15% are preferred.

The oxidized polyethylene wax emulsion is applied to yarn either undrawn or drawn, in any of the conventional ways of applying yarn finishes. A satisfactory manner of \applyingthe coating is by feeding the emulsion to a trough euqipped with a rotatable roll dipping therein, and passing the yarn in contact with this roll at a relative speed with respect to the rate of rotation of the roll adjusted to provide the desired pick-up of coating by the yarn, for example, between-about 1% and about 6% pick-up of the liquid coating by weight, based on the weight of the yarn. I p

The coated yarn may be heated, if desired, to a tem- 3 perature above about 100 C. for a short period, for example, a few seconds, preferably to between about 100 C. and about 135 C. to cause volatilization of part or all of the water in order to prevent shrinkage of the yarn when packaged by winding on cones, etc.

The amount of oxidized polyethyleen wax remaining on the yarn after the heat treatment should be sufficient to form at least a thin coating on the yarn. Even extremely thin coatings of oxidized polyethylene wax on the yarn result in significant reduction of the fibre to fibre friction of such yarns when fabricated into rope. Thus quantities equivalent to as little was about 0.05% the weight of the finished yarn impart excellent durability properties to the yarn. -I prefer, however, to apply. sufficient emulsion to produce coatings of between about .05% and about 2% by weight of the finished yarn. Larger proportions may be applied, up to or more, if desired.

The oxidized polyethylene wax emulsion may be applied to the yarn either alone, or together with other additives commonly applied to yarns as yarn finishes to improve their processability, for example, anti-static agents, mineral oil, silicones, etc. My coating differs from the usual spin finish additives, however, in that it produces a permanent finish rather than being washed out and removed as are the usual spin finishes applied for improving process-ability. In general, I prefer to apply the oxidized polyethylene wax emulsion as an after coating on drawn yarns, and find it especially adapted for treatment of polyamide filaments including nylon 6, polycaprolaotam, filaments.

Any suitable emulsifying agent may be used in preparing the oxidized polyethylene wax emulsions used in the process of my invention. Mixtures of higher fatty acids, for example C to C saturated aliphatic acids with volatile amines such as morpholine, methoxy propyl: amine, 2-amino-2-methyl-l-propanol, etc. may be used as emulsifiers as may also the long chain alkyl aryl sulfonates such as 'keryl benzene sodium sulfonate, dodecyl benzene sodium sulfonate, alkyl aryl polyether alcohols. ,Also useful are the general class of non-ionic emulsifiers especially the condensation products of ethylene oxide with hydrophobic material such as a long chain aliphatic alcohol, acid, ester, ether or alkyl phenol. These products are characterized by containing as the hydrophilic portion of the molecule, a plurality of oxyethylene moieties as illustrated in the fromulas below.

wherein R is an alkyl group having from 12 to 22 carbon atoms or an alkyl phenol residue wherein the alkyl group contains from 6 to 13 carbon atoms inclusive and wherein x is at least 4 especially between about 6 and about 40. p I

Commercial examples of products in this group include Triton X100 wherein R is an alkyl phenol residue wherein the alkyl group is isooctyl and wherein x is 7 to 9; Triton X-102 wherein R is an isooctyl phenol iresidue and x is 11; Tergitol NPX wherein R is ethylhexyl phenol residue and x is 8 to 9, Neutronic 600 wherein R is nonyl phenol residue and x is 9; Emulphor ELN wherein R is dodecyl phenol residue and x is 19.

(2) Condensation products of fatty acids and polyethylene glycols having the general formula wherein R is a long chain alkyl group having from 12 to 18 carbon atoms inclusive and x is an integer from 8 to 40 inclusive.

(3) Polyoxyethylene derivatives of hexitol anhydride or sorbi-tol fatty acid esters such as Tween 80.

(4) Polyoxyethylene ethers,

R-O (CH CH O CI-I CH OH wherein R is an alkyl group having from 6 to 18 carbon atoms and x is an integer from 4 i040 inclusive. A commercial product which is an example of this group is Brij 30 in which R is lauryl and x is believed to be 10.

The above others are well known commercial products, many specfiic examples of which are disclosed in German Patent 965,722, issued June 19, 1957.

Usually between about 15% and about 50% or more of emulsifier based on the weight of the oxidized polyethylene wax may be used.

The resulting treated continuous filament yarns are thus supplied with a coating of oxidized polyethylene wax evenly distributed upon the surface of the yarn and tenaciously adhering thereto forming a Water resistant coating which imparts to the yarn in addition to water resistance a low degree of fibre to fibre friction such that development of internal heat is insufficient to cause excessive disorientation and water erosion of the filaments.

The resulting oxidized polyethylene wax-coated yarns are especially adapted for fabrication into ropes of unusually high wet strength, by well known commercial processes. In preparing such continuous filament yarns for subsequent fabrication into ropes, the yarns are given a slight twist, for example /2 turn per inch. Ropes are prepared from such yarns by a multi-stage process, the steps of which may vary somewhat depending on the type of rope desired. In general, the first step involves forming strands by laying together a plurality of rope yarns, for example, 70-80 or more, in a left hand direction, i.e.'with an S or left hand lay or twist. The next step involves plying the desired number of the above strands, usually 3 or more, to form a rope with a Z twist or right lay in which, in general, no previously imparted twists are lost, and on occasion, additional twisting is produced. This procedure results in a finished rope r of linear structure composed of a limited number, usually 3 to 9 laid or twisted strands which strands are made up of a plurality of plies of twisted yarn, and in which the yarn is made up of a plurality of continuous filaments.

The following specific examples further illustrate my invention. Parts are by weight except as otherwise noted.

EXAMPLE 1 An aqueous emulsion of polyethylene wax of the following composition was prepared by melting the wax and the emulsifier togetherat .250 F., then cooling to 230 F. With the melt temperature at 230 F. the melt was added gradually with stirring to water which had been heated to just below boiling temperature. The oxidized polyethylene was a polyethylene/alkanol telomer wax having an average molecular weight between about 1,000 and about 2,000, an oxygen content of about 3%, melting .point 213-221 F. and acid number 14-17. The resulting emulsion was allowed to cool to room temperature and was placed in a trough into which dipped a rotatable finish roll. Next, an 840 denier, drawn nylon 6 yarn which had been treated with a conventional anti-static finish, was passed over the rotating roll as the yarn Was being unwound from a pirn and wound on a parallel package, at a rate so as to pick upabout 4% of liquid emulsion based on the weight of the yarn. The yarn was then heated to C. to evaporate water and emulsifier and distribute the wax evenly over the yarn, leaving about 0.67% of solids on the yarn.

The resulting coated yarn was subjected to tests to determine fibre to fibre friction according to the method described by Schlatter, Olney and Baer in Textile Research Journal, vol. XXIX, pp. 200-210 (March 1959). In this test treated yarn was hung at a 180 contact angle over a inch diameter pin which had been wrapped with similarly treated yarn. One end of the yarn was weighted (T The other end was fastened to the shaft of a constant rpm. drive. The frictional drag (T was recorded on a tensorneter located between the pin and the drive as the yarn was pulled over the pin at a speed of 1 /2 inch per minute. A similar test wasv carried out on untreated yarn, and on treated and untreated yarns which had been subjected to extraction with hot water with the results shown in Table I below wherein T T is a measure of the frictional force produced.

Table I FIBRE TO FIBRE FRICTION OF TREATED AND UNTREATED NYLON YARNS T Untreated Yarn Treated Yarn T T (Av.)"li r P -T1 As Drawn Water Extracted T =Initial load (grams). T =Frictional drag (grams). T T1=Frictional force produced (grams).

The untreated yarn exhibited decided stick-slip phenomena in all cases except at the lower level of initial load in the yarn as drawn. None of the treated yarns exhibited the stick-slip phenomenon.

It can be seen from the results in Table I, that the frictional force exerted by fibre to fibre contact at different'loads has been substantially reduced by my treatment.

EXAMPLE 2 In a second test the oxidized polyethylene wax emulsion described in Example 1 above was modified by the addition thereto of 0.5 part of a 10% water solution of a conventional anti-static agent and 0.5 part of 10% mineral oil in water emulsion. This composition was applied to drawn 840 denier nylon yarn in the same manner as in Example 1, with results shown in Table 11 below.

Table II lls Extracted Boiled Treated with in Water Water 1 hour 5 5 5 T 28-30 23 25 T (Av.)-T1 24 18 20 None of the treated yarns exhibited any stick-slip under any of the conditions employed. Both the water treated yarns (boiled and extracted) exhibited improved resistance to wetting due presumably to removal of water soluble components from the coating and attesting to the relative water resistance and permanence of the oxidized polyethylene wax finish.

8 EXAMPLE .3

An oxidized polyethylene wax emulsion was prepared as described in Example 1, producing an emulsion of the following composition 1 Percent by weight 1 Triton X-100, 1.e., condensation product of isooctyl phenol with 7-9 moles of ethylene oxide.

The emulsion was placed in a trough having a rotatable roll dipping therein. Over this roll was passed an 840 denier drawn nylon 6 continuous filament yarn which had already been coated with a standard spin f nish. The relative speeds of the roll and yarn travel were adjusted so that the yarn picked up an amount of wet coating equivalent to 2% the weight of the yarn. The yarn was then heated to 125 C. for about one second to remove excess water. The yarn was then cooled to about 25". C.

The above treated yarn was then fabricated into rope of the marine hawser type of 5 /2 inches circumference by a standard commercial rope making process.

Specimens of the rope thus prepared were subjected to standard evaluation tests in comparison with rope made in the same manner from a yarn similar in all respect-s to the treated yarn except that it had been given no oxidized polyethylene wax coating.

The strength tests were determined ner on an lnstron tester.

The Wet Repeat test was conducted by placing the rope specimen, under tension, between a bolted cross pin and a cross pin attached to the piston rod of an air cylinder. Asthe' piston rod makes the outward stroke, the specimen becomes slack and is dipped into a water tank free of tension, permitting water to penetrate into the rope. After about 10 to 15 strokes, the rope specimen is loaded at 30% of the breaking strength which is controlled by air pressure delivered to the cylinder. The cyclic strokes are continued and are recorded on a counter.

Results are shown in Table III below.

in standard man- Table III STRENGTH AND DURABILITY TESTS ON ROPES FROM TREATED AND UNTREATED NYLON YA RNS Untreated Treated Size:

Diameter, inches 1 1 62 Circurnt., inches 5. 48 5. 67

Lay, inches/l0 turns 47. 45.17 Weight:

Pounds/10 feet 7. 53 7. 88 Tensile Strength:

Dry strength lbs 70, 600 77, 667

Ratio, dry strength/Weight 9, 375 9, 855

Wet strength 69, 200 75, 467

Ratio, wet strength/dry strength. 98 97 Elongation, percent break 53. 6 58. 4 stlrgngth after 1,000 Wet repeat loads to 17,000

Pounds 35, 400 73, 800

Percent of orignial strength 50 It is apparent from the data in Table III that the rope made from yarns coated with oxidized polyethylene wax according to my invention has been spectacularly improved in durability under conditions of wet loading and chafing, the treated rope in this case having retained 95% of its original strength after enduring 1,600 repeated wet loading cycles under 17,000 pounds pressure whereas the untreated rope retained only 50% of its original strength after the same treatment.

1? EXAMPLE 4 Samples of inch diameter rope made by a standard commercial process from 856 denier nylon 6 yarn coated with a 0.6% solids coating of emulsifiable oxidized polyethylene wax applied as described in Example 3 above, were subjected, in comparison with a similar rope made from a yarn identical in all respects except for omission of the oxidized polyethylene wax treatment, to the wetrepeat loading test described in Example 3, to test its durability as compared to rope from untreated yarn.

After 300 cyclic strokes the rope made with the treated yarn of the invention remained soft and visually free of broken filaments while the rope made from identical untreated yarn was extremely hard and showed many broken filaments. After 1,000 repeat loads (wet) using a 3,700 pound load, the treated rope retained 100% of its original strength whereas the untreated rope failed after 902 cycles, thus retaining of its strength at the 1,000 repeat mark.

These ropes were also subjected to wet and dry flexing tests through an angle of 180 C. using a 640 pound Weight and measuring the number of flexes required to cause failure of the rope. Results are given below in Table IV.

Table IV Untreated Treated Dry test 51, 935 57, 543 Wet test 3, 291 8, 865

This test illustrates the superiority in resistance to flexing resulting from the treatment of the yarn according to my invention.

Instead of applying the oxidized polyethylene wax as an aqueous emulsion it may be dissolved in any of theusual hydrocarbon or halogenated hydrocarbon solvents in which it is soluble at elevated temperatures and applied hot to the yarn as a coating or finish in a manner similar to that used in applying the emulsion, evaporating the solvent and cooling the thus coated yarn. Suitable solvents include toluene, xylene, V.M. & P. naphtha, trichloroethylene, carbon tetrachloride, cyclohexanone, turpentine, etc.

While the above describes the preferred embodiments of my invention, it will be understood that departures may be made therefrom within the scope of the specification and claims.

I claim:

1. A process for increasing the durability of a synthetic continuous filament yarn which comprises applying to said yarn a water-resistant coating of an oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and an oxygen content between about 3% and about 9% by weight.

2. A process for increasing the wet-durability of a synthetic continuous filament nylon yarn which comprises applying to said yarn an aqueous emulsion of an oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and containing between about-3% and about 6% oxygen by weight, and thereafter heating said yarn to a temperature between about C. and about C., thereby providing a water resistant coating on said yarn.

3. A process for increasing the durability of a synthetic, continuous filamentyarn which comprises applying as a coating to said yarn a liquid dispersion of a readily emulsifiable oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and an acid number between about 10 and about 50, and thereafter removing the liquid to form a waterresistant coating.

4. A continuous filament nylon yarn having a waterresistant coating thereon of a readily emulsifiable oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and an acid number between about 10 and about 50.

5. A continuous filament nylon yarn having a waterresistant coating thereon of between about 0.05% and about 2% by weight of the finished yarn of an oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and oxygen content between about 3% and about 6% by weight.

6. A rope consisting essentially of a plurality of laid strands composed of a plurality of oppositely laid continuous filament yarns, said yarns having a water-resistant coating thereon of a readily emulsifiable oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and an acid number between about 10 and about 50.

7. A synthetic continuous filament yarn having a coating thereon of an oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and an oxygen content between about 3% and about 9% by weight.

8. The product according to claim 7 wherein the yarn is nylon yarn.

9. A rope consisting essentially of a plurality of laid strands composed of a plurality of continuous filament yarns, said yarns having a water-resistant coating thereon of an oxidized polyethylene wax having an average molecular weight between about 1,000 and about 3,000 and oxygen content between about 3% and about 9% by weight, the oxidized polyethylene wax being present on the yarn in an amount equal to between about-0.05% and about 2% by weight of the yarn.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS FOR INCREASING THE DURABILITY OF A SYNTHETIC CONTINUOUS FILAMENT YARN WHICH COMPRISES APPLYING TO SAID YARN A WATER-RESISTANT COAITNG OF AN OXIDIZED POLYETHYLENE WAX HAVING AN AVERAGE MOLECULAR WEIGHT BETWEEN ABOUT 1,000 AND ABOUT 3,000 AND AN OXYGEN CONTENT BETWEEN ABOUT 3% AND ABOUT 9% BY WEIGHT. 